Many electronic devices, such as, e.g., microcontrollers, central processing units (CPU), memory devices, and the like, require a defined supply voltage. A linear voltage regulator can be used to provide such a defined supply voltage from an input voltage that is higher than the desired supply voltage. A linear voltage regulator includes a pass device, such as a transistor, connected between a supply input for receiving the input voltage and an output for providing the defined supply voltage to a load. A control circuit controls the pass device such that the supply voltage corresponds to a desired voltage.
The voltage regulator should be capable of responding quickly to variations of the load that may cause variations of the output voltage. Conventional linear voltage regulators include a large off-chip output capacitor connected to the output of the voltage regulator. Large capacitors, however, are difficult to implement in integrated circuits, and the provision of an external (discrete) capacitor would increase the costs.
There is therefore a need to provide a linear voltage regulator that is fast and that does not require an external output capacitor.